What are you guys doing to make your LS' like the Revs and where are you redlining/loosing power at? Is it just good springs and slightly loose con rod bearingings? I'd really like the pro's advice here..? I'm about to start building the motor for my Turbo LS CRX and I want to make it pretty stout without going crazy. I realize this is an all motor forum and since revs are an all motor important thing as well as forced induction I'd like to hear it from the guys that are doing it. Also, how many miles on your rev happy LS?

 

If you study boosted power curves you'll notice that you don't have to rev really high to make power, you just need to make sure your turbo and exhaust is sized properly to your intended use. No motor "likes revs" per se but you can make them withstand them better. All motor applications usually need to turn a higher RPM than stock to make additional power. If you're building a motor for boost, some of your clearances will be a little different, mostly due to increased heat and expansion. Installing stronger rods and rod bolts help quite a bit. Valvetrain is only needed to support the cams you're running and their normal RPM range. Many people running boost run stock cams like GSR or ITR and don't need to run anymore than stock valvesprings because they aren't reving past stock redlines.

 

I thought upgrading valvesprings and retainers helped valve performance in the upper rpm range?

 

"Upper RPM" is relative. If an engine redlines at 7k Rpm stock, then aftermarket valvetrain can extend that by a few thousand RPM. if you"re not revving past the stock redline, then the stock stuff, if its not fatigued from 150k on use, will be fine.

The only thing I would say, after doing some LS heads and taking cross sectional measurements, is that I would never run a stock LS head on anything I wanted to make good power on. the dimensions are just not there, you'll be leaving lots of power on the table.

You also may get better responses in the forced induction forum.

 

Well, here's the reason I'm asking this. I know the LS motor (B18A or B) only revs up to about 7k. Turbo isn't going to kick in until 4ish, anything lower is going to produce alot of wheel spin. I'd like to be able to take it up to 8, 8.5..9. so I can stay on the pipe longer. From what I understand, to make an LS motor handle that kind of RPM, the need a slightly looser bearing about .0001, rods and bolts as stated previously and good springs to keep from floating. I just don't want to build a motor under the wrong assumptions. I'm not green at build motors - not even high revving motors. Built a lot of sportbike engines and I4s. But I've never built one to handle higher RPMS under boost.

Again, I realize this is the NA section but I know you guys tend to focus more on high RPM for the purpose of making power - what do you do in that case. Has anyone made their LS motor handle 9K?

Thanks!

 

just throw a vtec head on there. ls valvetrain leaves a lot to be desired.

 

If you have the proper cams like Crower 403's and they are degreed correctly for turbo applications and the springs and retainers to match, the engine can make power to 8500-9000 no problem. Crower 404's have a lobe that is about a Type R vtec lobe. Like other people have said a Vtec head is worth alot because of the head flow and port volume. I built a LS turbo once and was making 240whp swapped a Vtec head on it and it made 295whp. Just saying.

 

Wankel? Lol

+1 vote for VTEC head
Welcome to the NA section lol

 

RPM -- Ruins Peoples Motors
lol

 

lol but true

 

How do the dimensions of a P8R ports compare to the standard b18/b20 head?

 

YOU DONT NEED TO TURN 8K TO GET POWER FROM A LS-T. Sorry for the caps I just wanted to get that through to you. My buddy has a LS-T and runs it to 7k with the rev limiter at 7200. Since the flow of the head in lamens terms sucks it stops making power right around 7100. SO building a LS head to take 8k doesnt mean you will make power up there. The LS motor were intended for low end torque, not high RPM power. Take that for what its worth beings my buddies car is making 325whp on 16psi, all of which is below 7200 rpm on a bone stock block, 54 trim turbo.